Catalyst system for producing ethylene polymers

ABSTRACT

A catalyst for producing ethylene polymers in which a first component composed of titanium, vanadium, halogen, and OR groups, wherein R is selected from among alkyl, cycloalkyl, aryl, acyl, and combinations thereof, is combined with an organometallic compound. A method for producing a catalyst system in which an organoaluminum compound component is contacted with a component composition produced by reacting a mixture of titanium and vanadium compounds with an organometallic compound to form a product mixture which is then contacted with titanium tetrachloride. A method for producing polymers of ethylene by contacting ethylene with a catalyst system produced as above under conditions suitable for polymerization.

BACKGROUND OF THE INVENTION

This invention relates to the production of polymers of ethylene. In oneof its aspects this invention relates to catalyst systems suitable forproducing polymers of ethylene. In another of its aspects, thisinvention relates to the preparation of such catalyst systems.

A catalyst system for the production of polymers of olefins that can bedemonstrated to yield increased productivity of polymer as compared toother catalyst systems known in the art is of wide interest. Since it iswell-known that new combinations of known catalysts or a differentmethod for treating a catalyst composition can produce surprisingresults in catalyst activity or productivity, recombination of catalystingredients and novel treatment methods are constantly being initiated.As a result of such an effort, a new and useful catalyst system for theproduction of ethylene polymers has been discovered.

It is an object of this invention to provide a catalyst system for theproduction of ethylene polymers. It is another object of this inventionto provide a method for preparing a catalyst system for the productionof ethylene polymers. It is still another object of this invention toprovide a method for producing ethylene polymers.

Other aspects, objects, and the various advantages of this inventionwill become apparent upon reading this specification and the attachedclaims.

STATEMENT OF THE INVENTION

A catalyst is provided that is useful in conjunction with anorganoaluminum compound for producing ethylene polymers. The catalyst isa composition of titanium, vanadium, halogen, and OR groups, wherein Ris selected from among alkyl, cycloalkyl, aryl, acyl, and combinationsthereof, that is prepared by sequentially treating a mixture of titaniumand vanadium compounds with (1) an organometallic compound and (2)titanium tetrachloride.

In one embodiment of the invention, a method is provided for producing acatalyst useful in conjunction with an organoaluminum compound forproducing ethylene polymers. The method comprises: reacting a mixture oftitanium and vanadium compounds with an organometallic compound to forma product mixture which is then contacted with titanium tetrachloride toproduce a reaction product.

In further embodiments of the invention, the catalysts as describedabove are contacted with ethylene in the presence of an organoaluminumcompound under conditions suitable for polymerization to producepolymers of ethylene.

A catalyst system comprising a mixture of titanium and vanadiumcompounds treated sequentially with an organometal compound and atitanium tetrahalide to form component A, and an organoaluminum compounddesignated as component B, is used to produce ethylene polymersaccording to this invention. Hydrogen can be present in the reactorduring polymerization as is known in the art to regulate the molecularweight of the polymer. The resinous polymers formed are normally solidmaterials which can be readily converted into useful articles such asfilm, fibers, pipe, containers, and the like, by employing conventionalplastics fabrication equipment.

The titanium compounds used in preparing component A are described bythe formula Ti(OR)_(n) X_(4-n) in which R is a selected from amongalkyl, cycloalkyl, aryl, acyl groups and combinations thereof such asalkaryl. Each group can contain from 1 to about 20 carbon atoms permolecule. The subscript n designates 0,1,2,3 or 4 and X is bromide,chloride, or iodide, more usually bromide or chloride. Exemplarycompounds include titanium tetraacetate, titanium tetramethoxide,titanium tetraethoxide, titanium tetraeicosyloxide, titaniumtetracyclohexyloxide, titanium tetrabenzyloxide, titaniumtrimethoxidebutoxide, titanium ethoxytrichloride, titaniumdibutoxidedioctadecyloxide, titanium diisopropoxydibromide, titaniumphenoxytrichloride, titanium tri-o-xylenyloxychloride, titaniumtetrabromide, titanium tetrachloride and titanium tetraiodide. Atitanium alkoxide, particularly titanium tetraethoxide, is presentlypreferred.

The vanadium compounds used in preparing component A can be VX₄ or havethe general formula VO(OR')_(m) X_(3-m) in which R' is an alkyl groupcontaining from 1 to about 20 carbon atoms, m is 0 to 3 and X is asdescribed before. Representative compounds include vanadiumtetrachloride, trimethyl vanadate, triethyl vanadate, tridodecylvanadate, trieicosyl vanadate, diethoxy vanadium chloride, n-butoxyvanadium dibromide, vanadium oxytribromide and vanadium oxytrichloride.Vanadium oxytrichloride is presently preferred.

Although an effective catalyst can be formed without the presence of ORgroups, it is necessary that a combination of titanium, vanadium, --Xand --OR groups be present in order to achieve the best results. Thus,for example, a titanium alkoxide can be admixed with a vanadiumoxytrihalide or a titanium tetrahalide can be admixed with a trialkylvanadate. A presently preferred combination consists of titaniumtetraethoxide and vanadium oxytrichloride.

The mole ratio of vanadium compound to titanium compound can range fromabout 0.1:1 to about 10:1, more preferably from about 0.25:1 to about2:1 and even more preferably about 1:1.

Step 1 in forming component A is carried out by reacting the mixture oftitanium and vanadium compounds with an organometallic compound of GroupI-III of the Periodic Table of elements, Handbook of Chemistry andPhysics, Chemical Rubber Company, 54th edition, 1973, page B3, and, inparticular, with an organoaluminum compound selected from amongalkylaluminum alkoxides, dialkylaluminum halides, alkylaluminumdihalides and mixtures thereof including alkylaluminum sesquihalides.The number of carbon atoms in each alkyl group can range from 1 to about20. Exemplary compounds include dimethylaluminum bromide,diethylaluminum chloride, dioctylaluminum iodide, dieicosylaluminumchloride, ethylaluminum dichloride, dodecylaluminum dibromide,dioctadecylaluminum iodide, ethylaluminum sesquichloride,isobutylaluminum sesquibromide, diethylaluminum ethoxide, and the like.A presently preferred compound is ethylaluminum sesquichloride.

The mole ratio of organometallic compound to the mixture of titaniumplus vanadium compounds can be varied. However, it is preferred that thegram-atom ratio of aluminum to titanium plus vanadium range frm about0.5:1 to about 10:1, more preferably from about 0.7:1 to about 3:1.

The titanium and vanadium compounds are preferably admixed prior totheir reaction with the organometallic compound. Although the compoundscan be admixed neat, if liquids or if one is a liquid, this operationcan be performed in a dry hydrocarbon diluent. Suitable hydrocarbondiluents include paraffins such as pentane, n-hexane, and the like;cycloparaffins such as cyclopentane, methylcyclohexane and the like;aromatic hydrocarbons such as benzene, toluene and the like; ethers suchas diethyl ether, tetrahydrofuran, and the like; or mixtures thereof.Preferably, the admixture should age at least about two hours and evenmore preferably several days before the reaction is performed. Atemperature for the reaction can range from about -30° to about 150° C.and usually is in the range from about 0° to about 50° C., utilizingcooling as required to maintain the desired temperature. A reaction timeranging from about 0.5 to about 5 hours and generally from about 2 toabout 4 hours is employed in preparing samples for bench scale use.Following the reaction, the colored precipitate is filtered off, washedwith dry diluent, dried in a stream of dry, non-reactive gas such asnitrogen, argon, etc., or by evaporation and finally stored in a dry boxin an inert atmosphere until used.

Order of addition of the reagents used in the reaction is usually byslow addition of the organometallic compound to the mixture of titaniumand vanadium compounds. Good results in terms of polymer productivityare also realized by reverse addition of reagents. However, the bulkdensities of polymers prepared when using catalysts produced by thelatter method tend to be lower than those prepared by the firstdescribed preparation technique.

Step 2 in forming component A is carried out by contacting the productof step one with TiCl₄ at a temperature sufficient to provide areaction. The reaction temperature generally ranges from about 10° toabout 150° C. More preferred is a temperature range from about 20° toabout 120° C. A weight ratio of TiCl₄ to step 1 product ranging fromabout 10:1 to about 0.1:1, more preferably from about 7:1 to about0.25:1 is used. Generally, a hydrocarbon diluent, e.g. n-hexane orn-heptane, is also used in amounts ranging from about 2 to about 20parts by weight per weight of component A precursor to facilitate thetreating process. Treatment time can vary from about 0.1 to about 10hours, more preferably from about 0.5 to about 6 hours. Following thetreatment, component A is filtered off, washed with fresh portions ofdry diluent, and dried overnight by evaporation of solvent in a dry box.It is within the scope of the invention to repeat the TiCl₄ treatmenttwo or more times.

Component B of the catalyst system is an organoaluminum compound of theformula AlR"_(a) X'_(3-a) where R" represents hydrogen or an alkyl oraryl group containing from 1 to about 20 carbon atoms, X' is bromine,chlorine or iodine or an alkoxy group containing from 1 to about 12carbon atoms and a is an integer of 1 to 3. When X' is alkoxy, a is 2.Exemplary compounds include trihydrocarbyl aluminum compounds such astrimethylaluminum, triethylaluminum, tridodecylaluminum,trieicosylaluminum, triphenylaluminum, dihydrocarbylaluminum halidessuch as diethylaluminum chloride, dibutylaluminum bromide;hydrocarbylaluminum dihalides such as methylaluminum dichloride,isopropylaluminum dibromide; hydrocarbylaluminum alkoxides such asdimethylaluminum ethoxide, didodecylaluminum dodecyloxide; andhydrocarbylaluminum sesquihalides such as ethylaluminum sesquichloride.Presently preferred are trialkylaluminum compounds, particularlytriethylaluminum.

The molar ratio of component B to component A ranges from about 1:1 toabout 1500:1, preferably about 2:1 to about 1000:1, in terms ofAl/(Ti+V).

The polymerization process used for producing ethylene polymers,according to this invention, can be any of the well-known processesincluding batch and continuous processes. As an example of a batchprocess, a stirred autoclave can be prepared by first purging withnitrogen and then with isobutane. A cocatalyst solution containing anorganoaluminum halide and then a catalyst produced as set out above areintroduced into the reactor through an entry port under an isobutanepurge. The port is closed and hydrogen, if any, and isobutane are added.The autoclave is then heated to the desired reaction temperature in therange of about 50° C. to about 120° C. and the ethylene is thenintroduced and maintained at a partial pressure in the range of about0.5 to about 5.0 MPa. At the end of a designated reaction time, usuallyabout 0.5 to about 5 hours, the ethylene addition is terminated andunreacted ethylene and isobutane are vented. The reactor is then openedand the polyethylene product is collected as a free-flowing white solid.The polymeric product is air dried.

In a continuous process, a suitable reactor such as a loop reactor iscontinuously charged with suitable quantities of solvent or diluent,catalyst, cocatalyst, ethylene, hydrogen (if any), and comonomer (ifany). Reactor product is continuously withdrawn and solid polymerrecovered from it by suitable means such as by flashing.

EXAMPLE I

Preparation of a typical catalyst component A is performed as follows:In a dry box, 45.64 g (0.20 mole) of Ti(OC₂ H₅)₄ and 34.66 g (0.20 moleof VOCl₃ were mixed together yielding a red liquid. After standing abouttwo weeks, 40.14 g (0.10 mole) of the Ti(OC₂ H₅)₄.VOCl₃ mixture wascharged to a container along with 100 ml of dry n-hexane. The containerwas capped, removed from the dry box, placed in an ice bath and contentsagitated while 135 ml of 25 wt. % ethylaluminum sesquichloride (EASC) indry n-heptane, equivalent to 0.108 mole organoaluminum compound, wasadded over a 2 hour period. Thus, the mole ratio of EASC totitanium-vanadium compound mixture was about 1.1:1. Following thisoperation, the container was tumbled in a 30° C. bath for 17 hours,taken into a dry box, decapped, contents filtered and the brown coloredsolid washed with several portions of dry n-hexane. The resultingproduct was allowed to dry for several days by evaporation of thesolvent in the dry box. A portion of the step one solid was reserved fora subsequent polymerization test. For convenience the solid product fromstep one is referred to in the tables as S-1.

Individual portions of the step one product were then treated with amixture of titanium tetrachloride and dry n-hexane or n-heptane forseveral hours. The step two products were isolated by filtering, washedwith several portions of dry n-hexane and dried overnight by evaporationof the solvent as the products were stored in the dry box.

Step two treating conditions are presented in Table 1A. In eachinstance, 1.00 g of step one product was treated.

Ethylene was polymerized for one hour employing a reactor temperature of80° C. and a nominal reactor pressure of about 1.9 MPa (275 psig). Thepartial pressure of ethylene was held constant at 100 psig (0.69 MPa).The results obtained are given in Table 1B.

Component B consisted of 3 ml triethylaluminum (TEA) contained as a 15wt. % solution in dry n-heptane, giving a calculated amount of 2.76mmoles TEA used in each run.

                  Table 1A                                                        ______________________________________                                        Treating S-1 Composition With TiCl.sub.4                                      Com-          Wt.                                                             ponent                                                                              TiCl.sub.4                                                                            Ratio   Hydrocarbon                                                                             Time Temp.                                    A No. (g)     TiCl.sub.4 :S-1                                                                       (name) (ml) (hrs)                                                                              °C.                             ______________________________________                                                                                     Con-                             1     0       0        0          0     0    trol                             2     0.25    0.25:1  hexane 10   2    25                                     3     0.25    0.25:1  hexane 10   4    25                                     4     0.25    0.25:1  hexane 20   2    68                                     5     0.25    0.25:1  hexane 20   4    68                                     6     0.25    0.25:1  heptane                                                                              20   2    100                                    7     1.00    1:1     hexane 10   2    25                                     8     1.00    1:1     hexane 10   4    25                                     9     1.00    1:1     hexane 20   2    68                                     10    1.00    1:1     hexane 20   4    68                                     11    2.00    2:1     hexane 10   2    25                                     12    2.00    2:1     hexane 10   4    25                                     13    2.00    2:1     hexane 20   2    68                                     14    2.00    2:1     hexane 20   4    68                                     15    3.00    3:1     hexane 10   2    25                                     16    3.00    3:1     hexane 10   4    25                                     17    3.00    3:1     hexane 20   2    68                                     18    3.00    3:1     hexane 20   4    68                                     19    3.00    3:1     heptane                                                                              20   2    100                                    20    5.00    5:1     heptane                                                                              20   2    100                                    ______________________________________                                    

                  Table 1B                                                        ______________________________________                                        Ethylene Polymerization With Ti/V Catalysts                                   Component A      Com-           Calculated                                                                            Polymer                                    Wt.             ponent       Produc- Bulk                                     Ratio    Run    A     Polymer                                                                              tivity  Density                             No.  TiCl.sub.4 :S-1                                                                        No.    g     Yield, g                                                                             g/g A   g/ml                                ______________________________________                                         1.sup.(a)                                                                         0        10     0.0190                                                                              120     6,300  0.36                                 2   0.25:1   11     0.0130                                                                              298    23,000  nd.sup.(b)                           3   0.25:1   12     0.0150                                                                              531    35,000  0.38                                 4   0.25:1   13     0.0080                                                                              306    38,000  0.34                                 5   0.25:1   14     0.0124                                                                              460    37,000  0.36                                 6   0.25:1   15     0.0080                                                                              464    58,000  nd                                   7   1:1      16     0.0128                                                                              488    38,000  0.36                                 8   1:1      17     0.0098                                                                              341    35,000  0.34                                 9   1:1      18     0.0062                                                                              365    59,000  nd                                  10   1:1      19     0.0076                                                                              439    58,000  0.28                                10   1:1      20     0.0052                                                                              203    39,000  0.26                                11   2:1      21     0.0096                                                                              327    34,000  nd                                  12   2:1      22     0.0100                                                                              473    47,000  0.36                                13   2:1      23     0.0073                                                                              415    57,000  0.26                                13   2:1      24     0.0050                                                                              331    66,000  0.26                                14   2:1      25     0.0057                                                                              407    71,000  nd                                  14   2:1      26     0.0043                                                                              293    68,000  nd                                  14   2:1      27     0.0056                                                                              410    73,000  nd                                  15   3:1      28     0.0078                                                                              311    40,000  0.32                                16   3:1      29     0.0135                                                                              657    49,000  0.34                                17   3:1      30     0.0023                                                                              196    85,000  0.22                                18   3:1      31     0.0102                                                                              655    64,000.sup.(c)                                                                        0.26                                18   3:1      32     0.0050                                                                              308    62,000  0.24                                18   3:1      33     0.0053                                                                              443    84,000  0.24                                19   3:1      34     0.0068                                                                              542    80,000  nd                                  20   5:1      35     0.0069                                                                              589    85,000  nd                                  ______________________________________                                         Notes:                                                                        .sup.(a) No TiCl.sub.4 treatment, control run.                                .sup.(b) nd means not determined.                                             .sup.(c) 1.5 hour run.                                                   

Inspection of the data presented in Tables 1A and 1B reveals thatcompositions prepared from 1 to 1 molar ratios of Ti(OC₂ H₅)₄ and VOCl₃reacted with EASC and post treated with TiCl₄ are active ethylenepolymerization catalysts. Without such treatment the control catalystfor the series produce 6,300 grams polyethylene per gram catalystcomponent A per hour at 80° C. as the result in run 1 shows. Theremaining runs are grouped to show the effects of TiCl₄ treatment interms of wt. ratio TiCl₄ :reacted Ti/V composition at several treatmentconditions. In general, within each group, the most active catalystsresult when the TiCl₄ treatment occurs at about 68° C. or 100° C. for2-4 hours rather than a similar time at 25° C. The results also show,that a wt. ratio of TiCl₄ to S-1 composition of about 0.25:1 and evenmore preferably about 2:1 is desirable in the treating step to obtainhighly active catalysts.

EXAMPLE II

The influence of the reducing agent employed in forming catalystcomponent A, the order of addition of reagents and the effect of TiCl₄treatment is explored in this example.

Following the procedure described before, 22.82 g (0.10 mole) of Ti(OC₂H₅)₄ and 17.33 g (0.10 mole) of VOCl₃ were mixed together and stored ina dry box for at least 4 days before being used in the compositionsdescribed below.

Composition 1 was made by adding 25 mmoles of ethylaluminum dichloride(EADC, 1.65 molar in n-hexane) to a flask containing 10 mmoles of theTi/V mixture and 10 ml n-hexane over about a 3/4 hour period at aboutroom temperature. The mole ratio of EADC to Ti/V mixture was 2.5:1.After stirring 3 hours, the brown precipitate was filtered off, washedwith n-hexane and dried overnight by evaporation of solvent in a drybox.

Composition 1T was made by stirring 0.50 g TiCl₄ with 0.87 g composition1 (wt. ratio is 0.57:1) and 10 ml n-hexane for 3 hours at 25° C. Theproduct was isolated, washed and dried as described before.

Composition 2 was made with the same amounts of reagents at 25° C. in asimilar period of time as described in composition 1 except the Ti/Vmixture was added to the EADC solution. It was isolated, washed anddried as before.

Composition 2T was made by stirring 0.50 g TiCl₄ and 1.04 g ofcomposition 2 (wt. ratio is 0.48:1) and 10 ml n-hexane for 3 hours atroom temperature. The product was isolated, washed and dried as before.

Composition 3 was made at 25° C. by adding 12 mmoles of EASC, 25 wt. %in n-heptane, to a flask containing 10 mmoles of the Ti/V mixture and 20ml n-hexane over a period of about 1 hour. The mole ratio of EASC toTi/V mixture was 1.2:1. The mixture was stirred overnight (about 15hours). The product was isolated, washed and dried as before.

Composition 3T was made at 25° C. by stirring 0.50 g TiCl₄ with 0.86 gcomposition 3 (wt. ratio is 0.58:1) and 10 ml n-hexane for 3 hours. Theproduct was isolated, washed and dried as before.

Composition 4 was made at 25° C. with the same amounts of reagentsdescribed in composition 3 except that the Ti/V mixture was added to theEASC solution and n-hexane in the flask in about 3/4 hour. The mixtureafter stirring for 5 hours was isolated, washed and dried as before.

Composition 4T was made at 25° C. by stirring 0.50 g TiCl₄ with 0.62 gcomposition 4 (wt. ratio is 0.81:1) and 10 ml n-hexane for 3 hours. Theproduct was isolated, washed and dried as before.

Composition 5 was made at 25° C. by adding 25 mmoles of diethylaluminumchloride (DEAC, 25 wt. % in n-hexane) to a flask containing 10 mmoles ofthe Ti/V mixture and 20 ml of n-hexane over a 1 hour period. The moleratio of DEAC to Ti/V mixture was 2.5:1. Stirring was continued for 4hours after which the product was isolated, washed and dried as before.

Composition 5T was made at 25° C. by stirring 0.50 g TiCl₄ with 0.81 gof composition 5 (wt. ratio is 0.62:1). The product was isolated, washedand dried as before.

Composition 6 was made at 25° C. by adding 10 mmoles of the Ti/V mixtureto a flask containing 24.6 mmoles of the DEAC solution and 20 mln-hexane over 3/4 hour with stirring. Stirring was continued for 5 hoursafter which the product was isolated, washed and dried as before.

Composition 6T was made at 25° C. by stirring 0.50 g Ticl₄ with 0.70 gof composition 6 (wt. ratio is 0.71:1) for 3 hours. The product wasisolated, washed and dried as before.

A portion of each catalyst composition was used in combination with 3 mlTEA solution, equivalent to 2.76 mmoles TEA, to polymerize ethylene asbefore at 80° C. in the absence of hydrogen. Each run was 1 hour inlength unless specified otherwise. The conditions used and resultsobtained are given in Table 2. The nominal reactor pressure was 275 psig(1.9 MPa) with an ethylene partial pressure of 0.69 MPa.

                                      Table 2                                     __________________________________________________________________________    Ethylene Polymerization Results                                               Component A                                                                   Composition                Polymer                                                                            Calculated                                       Wt. Ratio                                                                           Run                                                                              Component A                                                                          Step 1  Yield                                                                              Productivity                                  No.                                                                              TiCl.sub.4 :S-1                                                                     No.                                                                              g      Reducing Agent                                                                        g    g/g A/hr                                                                             Remarks                                __________________________________________________________________________    1  0     33 0.0138 EADC    245  17,800 control                                1T 0.57:1                                                                              33A                                                                              0.0144 EADC    475  33,000 invention                              3  0     34 0.0230 EASC    256  11,100 control                                3T 0.58:1                                                                              34A                                                                              0.0180 EASC    692  38,000 invention                              3T 0.58:1                                                                              34B                                                                              0.0093 EASC    300  32,000 invention                              5  0     35 0.0188 DEAC    157   7,000.sup.(a)                                                                       control                                5T 0.62:1                                                                              35A                                                                              0.0100 DEAC    189  19,000 invention                              2  0     36 0.0091 EADC    119  14,000 control                                2T 0.48:1                                                                              36A                                                                              0.0086 EADC    242  28,000 invention                              4  0     37 0.0103 EASC    206  20,000 control                                4T 0.8:1 37A                                                                              0.0095 EASC    537  57,000 invention                              4T 0.8:1 37B                                                                              0.0105 EASC    410  39,000 invention                              6  0     38 0.0235 DEAC    132   5,600 control                                6T 0.71:1                                                                              38A                                                                              0.0107 DEAC    505  47,000 invention                              6T 0.71:1                                                                              38B                                                                              0.0170 DEAC    727  43,000 invention                              6T 0.71:1                                                                              38C                                                                              0.0097 DEAC    677  70,000.sup.(b)                                                                       invention                              __________________________________________________________________________     Notes:                                                                        .sup.(a) 72 min. run yielded 8350 g, calc. for 60 min. gives 7000 g.          .sup.(b) 2 hour run.                                                     

The results given in Table 2 demonstrate that the titanium/vanadiummixture can be reacted with various alkylaluminum halide compounds toobtain solid products, which after treatment with TiCl₄, are activepolymerization catalysts. The beneficial effects of the TiCl₄ treatmenton catalyst activity are clearly shown in those run numbers followed bythe letter A, B or C in comparison to the appropriate control runsignified by a number only. The productivity values suggest that themost active component A is formed when EASC is used to react with theTi/V mixture.

Reproducibility of productivity values in terms of grams of polymer pergram component A per hour obtained with the catalyst systems are shownin runs 34A and 34B in which an average productivity of 35,000 isobtained. Thus, the two runs deviate about ±8% from the average.Similarly for runs 38A and 38B an average productivity of 45,000 isobtained. The two runs deviate about ±5% from the average. In performingsimilar calculations for runs 37A and 37B, an average productivity of48,000 is obtained. The two runs deviate about ±18% which is felt to beabnormally large since results of about ±10% or less are considered tobe acceptable in bench scale runs. The reason for this is not known butmight be accounted for by different poison levels in each run.

Run 38C is a 2 hour run. The results show the catalyst system tocontinue its activity for polymerizing ethylene beyond 1 hour. Anaverage of productivity results for runs 38A and 38B show an average of45,000 g polymer per g component A per hour. The same system is shown toproduce 70,000 g polymer per g component A in 2 hours.

In summary, a high yield ethylene polymerization catalyst is disclosedwhich is prepared by reacting a Ti(OC₂ H₅)₄.VOCl₃ mixture with anorganoaluminum compound to form a solid which is then treated with Ticl₄to produce an active catalyst. When the catalyst is used with TEA ascocatalyst to polymerize ethylene, polymer yields as high as 85,000 gramper gram catalyst (component A) per hour have been observed. At thisproductivity level, it is calculated that the resulting polymer wouldcontain less than about 3 ppm titanium plus vanadium and less than about5 ppm chloride ion. Such low levels of catalyst residues suggest it maynot be necessary to attempt removing them from the polymer, thusproviding a significant economic advantage.

EXAMPLE III

In a dry box containing a 100 ml flask equipped with a stir bar and astopper was added 2.28 g (10 mmoles) of Ti(OC₂ H₅)₄, 1.73 g (10 mmoles)VOCl₃ and 20 ml of dry n-hexane and the mixture was stirred 3 hours atroom temperature. Then 12.5 ml of 25 wt. % EASC solution (10 mmolesEASC) was added over a 1 hour period while stirring and stirring wascontinued overnight (about 16 hours). The mixture was filtered, theprecipitate washed with n-hexane and the product (G) dried overnight byevaporation of the solvent.

A 1.62 g portion of the product was stirred for 3 hours at roomtemperature with 0.50 g TiCl₄ and 10 ml of dry n-hexane. The weightratio of TiCl₄ step 1 composition was 0.3:1. The resulting product (H)was filtered, washed with dry n-hexane and dried as above.

Each product was analyzed and the active metal contents determined. Forconvenience, each metal is given in terms of wt. %, calculated as theelement.

    ______________________________________                                                Wt. %           Mole Ratio                                            Sample    Ti       V        Al    Ti/V                                        ______________________________________                                        G          9.4     10.9     5.3   0.87                                        H         10.8     11.1     4.2   0.98                                        ______________________________________                                    

The results indicate that not all of the starting titanium is recoveredsince the initial Ti/V mole ratio of 1:1 is decreased to 0.87:1 incomposition G. When this composition is treated with TiCl₄ and excessTiCl₄ is removed by washing the results show that a composition isformed that has a Ti/V mole ratio of about 1:1.

When the TiCl₄ treatment entails higher treating temperatures and higherweight ratios of TiCl₄ to step 1 composition such as those described inExample I, the amount of TiCl₄ fixed onto the step 1 composition isincreased somewhat. In general, the increased percentage of contained Tiranges from about 1% to 10%. Concurrently, the V and Al percentagesexperience a decrease of about 1% to 4%.

Samples of G and H were used to polymerize ethylene for 1 hour at 80° C.in the manner described earlier. The amount of catalyst and cocatalystused and the results obtained are shown below.

    __________________________________________________________________________    Catalyst                                                                                calculated   Calculated                                                                           Polymer                                                                            Calculated                                           mmoles                                                                              Cocatalyst                                                                           Mole Ratio                                                                           Yield                                                                              Productivity                               description                                                                         wt.g.                                                                             Ti V  TEA mmoles                                                                           Al/(Ti + V)                                                                          g    g/g A                                      __________________________________________________________________________    G     0.0153                                                                            0.030                                                                            0.033                                                                            2.76   44:1   177  12,000                                     H     0.0200                                                                            0.045                                                                            0.044                                                                            2.76   31:1   610  31,000                                     __________________________________________________________________________

The results clearly show in comparison to untreated catalyst that posttreating a step 1 composition with TiCl₄ and using the recoveredcatalyst with a cocatalyst to polymerize ethylene results in almost athree-fold improvement in productivity based in g polymer per g catalystcomponent A per hour.

EXAMPLE IV

A reacted Ti/V composition was prepared as before by treating a 1:1molar composition of Ti(OC₂ H₅)₄ -VOCl₃ (12.03 g, 30 mmoles) in 100 mlof dry n-hexane contained in a flask with 45 ml of 25 wt. % EASC inn-heptane (36 mmoles EASC) over a 45 minute period at 0° C. (ice bath).The flask was removed from the ice bath and the mixture was stirredovernight. The step 1 product was isolated, washed and dried in a drybox to yield a brown powder weighing 13.55 grams.

The 13.55 g step 1 product was added to 40 ml of dry n-hexane containedin a flask at room temperature and stirred while 2.0 g of TiCl₄ wasadded. Stirring was continued for 3 hours. The step 2 product wasisolated, washed and dried as before to yield 14.18 g of a brown powderysolid. The TiCl₄ -step one wt. ratio was 0.15:1. The step 2 operationwas performed in a dry box. This product is designated S-2.

In a dry box, 2.36 g of the step 2 product was charged to a flask alongwith 10 ml of dry n-hexane and 0.50 g of TiCl₄. The TiCl₄ to step 2product weight ratio was 0.21:1. The mixture was stirred for 3 hours atroom temperature and the product isolated, washed and dried to yield abrown powdery solid. Some of the product was lost during transfer to avial, hence an accurate weight of the product was not obtained. However,2.07 g of product was recovered. This product is designated as S-2+1.

Samples of the catalysts were tested for ethylene polymerization in themanner described before. Each test was performed at 80° C. for 1 hourusing 3 ml of the same TEA solution. The results are given in Table III.

                  Table III                                                       ______________________________________                                        Ethylene Polymerization                                                                    Polymer                                                                                     Bulk   Catalyst                                    Run  Catalyst      Yield   Density                                                                              Productivity                                No.  description                                                                             wt.g.   g     g/cc   g PE/g cat/hr                             ______________________________________                                        1    S-2       0.0103        nd     24,100                                    2    S-2       0.0067        nd     22,200                                    3    S-2       0.0096        nd     22,100                                                                        22,800 ave.                               4    S-2+1     0.0074        0.34   44,200                                    5    S-2+1     0.0082        nd     47,900                                    6    S-2+1     0.0075        nd     40,000                                                                        44,000 ave.                               ______________________________________                                    

The productivity results show that a two-stage treatment of a step 1product with TiCl₄ (runs 4-6) can substantially increase thepolymerization activity of the catalyst compared to a single stagetreatment (runs 1-3).

The results also suggest that if a single treatment of step 1 productwith TiCl₄ yields a catalyst having relatively poor activity that theactivity can be increased by one or more additional TiCl₄ treatments.

EXAMPLE V

A step 1 Ti/V composition was prepared by treating 60.21 g (0.15 moles)of a composition consisting of equal molar amounts of Ti(OC₂ H₅)₄ andVOCl₃ with 225 ml of 25 wt. % EASC (0.2 mole) in the manner previouslydescribed. Eight such batches were prepared plus a lesser batch about2/3 as big but using the same ratio of components. The step 1compositions were isolated, washed and dried as before. Portions of thecompositions were combined and mixed to yield 3 batches of the step 1catalyst. One batch weighing 150 g was charged to a flask and contactedwith 148 g of TiCl₄ and 300 ml of n-hexane and the stirred mixture washeated for 2 hours at 68°-70° C. After cooling to about 30°-35° C. theflask and contents were transferred to a dry box and solid productrecovered by filtration, washing with n-hexane and drying about 2 daysto obtain a brown powdery solid weighing 190.5 grams. The weight ratioof TiCl₄ to step 1 composition was 0.99:1. The other two batchesweighing 150 g each were individually treated with 150 g TiCl₄ and 400ml of n-hexane and reacted, isolated, washed and dried as in the firstbatch to obtain brown powdery solids weighing 185.5 grams for batch 2and 185.6 grams for batch 3. All batches were then combined. A samplewas partially analyzed and found to contain 15.7 wt. % Ti and 7.9 wt. %V. The aluminum and chloride components were not determined.

The final catalyst was prepared by mixing each 25 g portion of the step2 catalyst with 100 g of dry, powdered polyethylene sieved through a 50mesh (U.S. Sieve series) screen.

Ethylene and 1-hexene were copolymerized by contact with thepolyethylene-diluted catalyst in a continuous process employing a 26 gal(98 1) loop reactor in the manner known in the art. Isobutane was usedas diluent, triethylaluminum was used as cocatalyst and molecularhydrogen was used to adjust the molecular weight of the polymer.

At steady state conditions, the hourly feed rates were: isobutane, 7.9gal (30 l); ethylene, 16.6 lbs (7.53 kg); 1-hexene, 2.37 lbs (1.08 kg);catalyst, 0.00047 lbs (0.21 g) and triethylaluminum cocatalyst, 0.001lbs (0.45 g). The ethylene content in the reactor was calculated to be7.0 mole %, the hydrogen content in the reactor was calculated to be0.62 mole %. Reactor product was continuously withdrawn and thepolyethylene was recovered by flashing away isobutane diluent andmonomers. The copolymer was produced at the rate of 16.6 lbs/hr at acalculated productivity of 35,000 lbs copolymer per lb polyethylenediluted catalyst. The copolymer was found to have a density of 0.947g/cc and a melt index of 2.5 (ASTM D 1238-65T, condition E).

I claim:
 1. A catalyst useful in conjunction with an organoaluminumcompound for producing ethylene polymers, said catalyst comprising acomposition of titanium, vanadium, and halogen groups prepared bysequentially treating a mixture of titanium and vanadium compounds with(1) an organometallic compound and (2) titanium tetrachloride whereinsaid titanium compound is described by the formula Ti(OR)_(n) X_(4-n) inwhich R is selected from among alkyl, cycloalkyl, aryl, and acyl groupsand combinations thereof; each group can contain from 1 to about 20carbon atoms per molecule; n designates 1, 2, 3, or 4; and X is bromide,chloride, or iodide and the vanadium compound is VX₄ or VO(OR')_(m)X_(3-m) in which R' is an alkyl group containing from 1 to about 20carbon atoms, m is 0 to 3 and X is bromide, chloride or iodide.
 2. Acatalyst of claim 1 wherein m is 1-3.
 3. A catalyst of claim 1 whereinthe organometallic compound is an organoaluminum compound selected fromamong dialkylaluminum halides, alkylaluminum dihalides, alkylaluminumalkoxides, and mixtures thereof.
 4. A catalyst of claim 1 wherein saidtitanium compound is chosen from among a titanium tetraacetate, titaniumtetramethoxide, titanium tetraethoxide, titanium tetraeicosyloxide,titanium tetracyclohexyloxide, titanium tetrabenzyloxide, titaniumtrimethoxidebutoxide, titanium ethoxytrichloride, titaniumdibutoxidedioctadecyloxide, titanium diisopropoxydibromide, titaniumphenoxytrichloride, and titanium tri-o-xylenyloxychloride, and saidvanadium compound is chosen from among vanadium tetrachloride, trimethylvanadate, triethyl vanadate, tridodecyl vanadate, trieicosyl vanadate,diethoxy vanadium chloride, n-butoxy vanadium dibromide, vanadiumoxytribromide and vanadium oxytrichloride.
 5. A catalyst of claim 3wherein said organoaluminum compound is chosen from amongdimethylaluminum bromide, diethylaluminum chloride, dioctylaluminumiodide, dieicosylaluminum chloride, ethylaluminum dichloride,dodecylaluminum dibromide, dioctadecylaluminum iodide, ethylaluminumsesquichloride isobutylaluminum sesquibromide, and diethylaluminumethoxide.
 6. A catalyst system useful for producing ethylene polymerscomprising as component A a catalyst of claim 1 and as component B anorganoaluminum compound having the formula AlR"_(a) X'_(3-a) wherein R"is hydrogen or an alkyl or aryl group containing from 1 to about 20carbon atoms, X' is bromine, chlorine, or iodine or an alkoxy groupcontaining from 1 to about 12 carbon atoms, a is an integer of from 1 to3, and when X' is alkoxy, a is 2 with the molar ratio of component B tocomponent A in a range from about 1:1 to about 1500:1.
 7. A catalystsystem of claim 6 wherein said organoaluminum compound of component B ischosen from among trimethylaluminum, triethylaluminum,tridodecylaluminum, trieicosylaluminum, triphenylaluminum,diiethylaluminum chloride, dibutylaluminum bromide, methylaluminumdichloride, isopropylaluminum dibromide, dimethylaluminum ethoxide,didodecylaluminum dodecyloxide, and ethylaluminum sesquichloride.
 8. Amethod for producing a catalyst useful in conjunction with anorganoaluminum compound for producing ethylene polymers, said methodcomprising:(1) reacting a mixture of a compound of titanium having theformula Ti(OR)_(n) X_(4-n) in which R is selected from among alkyl,cycloalkyl, aryl, and acyl groups and combinations thereof; each groupcan contain from 1 to about 20 carbon atoms per molecule, n designates1, 2, 3, or 4; and X is bromide, chloride or iodide and a compound ofvanadium having the formula VX₄ or VO(OR')_(m) X_(3-m) in which R' is analkyl group containing from 1 to about 20 carbon atoms, m is 0 to 3 andX is bromide, chloride or iodide with an organoaluminum compound havingthe formula AlR"_(a) X_(3-a) wherein R" is hydrogen or an alkyl or arylgroup containing from 1 to about 20 carbon atoms, X' is bromine,chlorine, or iodine or an alkoxy group containing from 1 to about 12carbon atoms, a is an integer of from 1 to 3, and when X' is alkoxy, ais 2 thereby forming a first product and (2) contacting said firstproduct with a titanium tetrachloride to produce a second reactionproduct.
 9. A method of claim 8 wherein said titanium and vanadiumcompounds are mixed prior to contact with said organoaluminum compound.10. A method of claim 9 wherein a hydrocarbon diluent is admixed withsaid titanium-vanadium compounds.
 11. A method of claim 8 wherein saidproduct mixture is aged before being reduced with said organoaluminumcompound.
 12. A method of claim 8 wherein titanium tetrachloride isadded to the product.
 13. A method of claim 8 wherein said product isadded to titanium tetrachloride.
 14. A method for producing ethylenepolymers comprising contacting ethylene under conditions suitable forpolymerization with a catalyst comprising the catalyst of claim 1 and anorganoaluminum compound.